Storage area networks are dedicated networks for enabling multiple applications on servers access to data stored in consolidated shared storage infrastructures. Enterprises are deploying increasingly large-scale SANs in order to gain economies-of-scale business benefits, and are performing and planning massive business-critical migration processes to these new environments
Enterprise SANs are increasingly supporting most of the business critical applications in enterprises. These SAN are increasingly large and complex. A typical SAN environment in a Fortune 500 company may contain a few hundred servers and tens of switches and storage devices of different types. Furthermore these SAN environments are undergoing a large amount of change and growth. According to a recent Gartner survey, large scale SAN are growing on average by about 40% annually.
This large size and rate of growth of SANs leads to huge added complexity. The number of components and links which may be associated with the data transfer from each given application and one or more of its data units (LUNs—stored on one or more shared storage devices) may increase exponentially with the size of the SAN.
This complexity, which is compounded by the heterogeneity of the different SAN devices, leads to high risk and inefficiency. Changes to the SAN (which need to happen often due to the natural growth of the SAN) take a long time to complete by groups of SAN managers, and are error-prone. For example, many existing enterprises a routine change (such as adding a new server to a SAN) may take 1-2 weeks to complete, and a high percentage of these change process (sometime as high as 30-40% ) include at least one error along the way. It is estimated that around 80% of enterprise outage events are a result of some infrastructure change related event.
One of the main reasons for these problems in SANs is a consequence of the fact that applications and data luns, the end-points in SAN flows, have a relatively strong exclusive access relationship. That is, Each application on a SAN-connected host typically requires access (often exclusive access) only to some specific SAN data units (LUNs). Consequently, in storage area networks each source end point (application on a host) will typically need to interact only (and often exclusively) with a specific, small minority of target end points (LUNs on storage devices), ever.
However that access relationship and its related access characteristics actually need to be realized by setting up multiple underlying devices of different types. These underlying operations include multiple physical and logical basic set up actions (sometime tens per a single logical change) which need to be set up in different locations and device types, with perfect mutual consistency.
Currently there are no adequate technological solutions to assist the SAN administrators in establishing the end to end consistency of SAN states and change activities, in relation to the application-data requirements. The reality is that SAN administrators currently need to rely on manual methods, spreadsheet based information, and trial and errors.
There are important challenges that need to be overcome for such a technology to be developed. These challenges are related, among others, to the exponential number of potential access routes from application servers to the data storage devices, the high level of heterogeneity among SAN devices, the distributed nature of the required consistent snapshot state, and the fact that various type of events can occur and each can in principle affect any number of application to data flows. Therefore, there is a need for a solution to the problem of validating the end to end SAN state and of SAN state change events.